About sixty-six million years ago, a scene of unimaginable horror played out in a North Dakota floodplain landscape now well known as the Hell Creek Formation.
It came without warning; The earth shook violently with the seismic waves that resulted from an impact with a magnitude 10 or 11 earthquake, and deadly glass beads rained down from the sky like tiny ballistic missiles flying 200 miles an hour.
But for the Cretaceous in Hell Creek The waves were the most devastating.
Through six years of site excavation, a paleontologist has finally confirmed what he had long suspected – in the heart of North Dakota lies a prehistoric "killing field," perhaps the best evidence of events occurring during the most notorious mass extinction Earth have taken place.
Fossil fish, vegetation, mammals, insects, marine reptiles, and even a portion of a triceratops lay piled on top of each other, keeping the moment for eternity half a meter. The wall of water pelted the landscape and buried all sentient beings on their way.
According to paleontologist Robert DePalma, this is the first "mass extinction" of great life forms. It has always been found to be dinosaur extinction.
Fossil fish, mammals, insects, marine reptiles and part of a triceratops lie on top of each other, preserving the moment for eternity, a 30-foot wall of water bouncing off living beings on their way across the landscape , An Artistic Impression of the Scene is Shown
A TIME LINE OF THE EXTINCTION EVENT
Researchers estimate that seismic waves hit the Hell Creek Formation within 10 minutes prior to Chicxulub's asteroid impact 66 million years ago.
These would have been the equivalent of the waves of magnitude 10 or 11 earthquakes.
The team suspects that at least two massive waves, called seiches, followed.
These had affected the country in only about 20 minutes and eventually fell over six deposits on the damned creatures at the site.
Deadly glass beads, called tektites, rained down from the sky like little ballistic missiles flying 200 miles an hour.
The fossil record indicates that these beads continued to surface 10 to 20 minutes after the first wave, before a second blow buried the stranded fish in sand and gravel.
This thick deposit was finally sealed with a layer of iridium-ri ch clay – a material that is rare on Earth but commonly found in asteroids and comets.
It's not just another repository of chalk fossils – the scene discovered in the area now known as Tanis outcrop could be the Holy Grail.
At no other KT boundary [end of the Cretaceous Period] on earth can you find such a collection consisting of a large number of species representing the age of organisms and different stages of life, all of which died at the same time on the same day. "Said DePalma, curator of paleontology at the Palm Beach Museum of Natural History in Florida and a doctoral student at the University of Kansas.
During the Cretaceous, the Hell Creek Formation housed an inland sea, in which all sorts of climes lived prehistoric life, from Mosasaurs to snail-like cephalopods, called ammonites.
When the asteroid hit thousands of miles, a tsunami-like wave occurred, temporarily reversing the flow of a nearby river, and hundreds of them swirled thousands of sturgeon and paddle fish into the countryside.
There, the fish on the sandbank were hurled by high-speed glass beads, the so-called tektites, which rained down from the sky as a product of rocks melted during the impact. [19659002ByPaddlefishtectiteshavebeenanchoredinthegillsprobablyduetoseepagebywater-swimmerswithopenmouthsandinfeed-rakingwhichmeansthattheywere"thefirstdirectvictimsoftheimpact"
All this can be seen in the Hell Creek fossilized deathbed.
"It's like a museum at the end of the Cretaceous era in a layer one and a half feet thick," said Mark Richards, professor of Earth and Space Sciences at the University of Washington.
When the asteroid struck thousands of miles, a tsunami-like wave erupted that temporarily reversed the flow of a nearby river, throwing hundreds or thousands of sturgeon and paddle fish ashore. A fishtail from the Tanis deposit can be seen above
DePalma and colleagues, including researchers from the University of California, Berkeley and the Vrije Universiteit in Amsterdam, have described their remarkable details, test results reported next week in the Ze It will be published in the Proceedings of the National Academy of Sciences.
The fossil record shows that glass beads rain for 10 to 20 minutes after the first wave After a second hit, the stranded fish were buried in sand and gravel.
"The seismic waves start within nine to ten minutes of the impact, so they had a chance to slosh the water before all the globules had fallen out of the sky," Richards said.
These globules entered the surface, made funnels – one can see the deformed layers in previously soft mud – and then the debris covered the beads. Nobody has seen these funnels before. "
. "Tsunami from Chicxulub impact is certainly well documented, but no one knew how far that would go inland," DePalma said. The team found that there were at least two massive waves that destroyed the country at about twenty minutes
. DePalma has been digging in Hell Creek since 2013. And since then, his team has identified fish, burnt tree trunks. Coniferous branches, dead mammals, Mosasaur bones, insects, the carcass of a triceratops, marine microorganisms, dinoflagellates, and ammonites in the cemetery of the Cretaceous.
. Walter Alvarez and Robert DePalma are pictured on the Tanis outcrop in North Dakota
. The researchers say that seismic waves hit the area within 10 minutes of impact. a standing wave driven in the inland sea.
Meanwhile, the tektites fell at a speed of 100 to 200 miles per hour.
"One can imagine being polluted by these G's," Richards said.
"They could have killed you."
The team suspects that there were at least two massive waves known as "Seiches" that affected the country in just about 20 minutes and ultimately drove more than six feet of sediment to the surface of the damned creatures on the ground ,
This thick deposit is sealed with a layer of iridium-rich clay – a material that is rare on Earth, but common in asteroids and comets.
"Tsunamis from the clash of Chicxulub are certainly well documented, but nobody knew how much that would get into an inland sea," said DePalma.
The team has identified fish, burnt tree trunks, coniferous branches, dead mammals, Mosasaurus bones, insects, triceratops, marine microorganisms known as dinoflagellates in Cretaceous Cemetery. Fish Carcasses and Two Collapsed Logs Are Shown Above
"When Mark came aboard, he discovered a remarkable artifact – that the incoming seismic waves would have arrived from the point of impact at about the same time as the atmospheric travel time of Ejecta," said DePalma.
& # 39; That was our big break. #
The amazing discovery now provides a direct insight into the so-called KT boundary – or the end of the Cretaceous and the beginning of the Tertiary Period.
Hell Creek's stacked and fossilized bodies are just a fraction of the widespread devastation that resulted from the Chicxulub impact. When the asteroid struck, 75 percent of life on Earth was wiped out.